Comparative structural and techno‐functional elucidation of full‐fat and defatted flaxseed extracts: implication of atmospheric pressure plasma jet

Abstract

BACKGROUND:The relatively inferior techno-functionality of flaxseed protein/polysaccharide complexes, especially regarding emulsifying and antioxidant activities, has partially limited their implication in the health food system. The present study aimed to investigate the effects of an atmospheric pressure plasma jet (APPJ) on the physicochemical, structural and selected techno-functional properties of flaxseed extracts. RESULTS:The results obtained showed that the full-fat and defatted flaxseed extract solutions (5 mg mL -1 ) displayed a sustainable decline in pH (−54.06%, −48.80%, P < 0.05) and zeta potential values (−29.42%, −44.28%, P < 0.05), but a gradual increase in particle sizes, as visualised by an optical microscope, during 0-120 s of APPJ treatment. Moreover, the APPJ led to initial decrease but subsequent increase in protein carbonyls and secondary lipid oxidation products, and concurrently changed the spatial conformation and microstructure of flaxseed extracts, as indicated by endogenous fluorescence properties and scanning electron microscopy (SEM). Additionally, the protein subunit remodeling and gum polysaccharides depolymerization were different for full-fat and defatted flaxseed extracts after 30 s of APPJ exposure. Importantly, the emulsifying and antioxidant activities of defatted flaxseed extract were particularly improved, as assessed by cyro-SEM and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity following 15-30 s of APPJ treatment, as a result of the changing interactions between protein and gum polysaccharides, as well as the release of specific phenolic compounds.CONCLUSION: APPJ could serve as a promising strategy for tailoring the specific techno-functionality of flaxseed extracts based on mild structural modification.

Comparative Composition Structure and Selected Techno-Functional Elucidation of Flaxseed Protein Fractions

“…The total phenolic acids and flavonoids of extracts were determined using the Folin-Ciocalteu and aluminum nitrate assays. The results were expressed as mg gallic acid (GAE) and rutin equivalents (RE) per 100 g protein sample (dry basis), respectively [25]. The free phenolic acids of extracts were analyzed using an Agilent 1290 ultrahigh performance liquid chromatograph (Agilent, Santa Clara, CA, USA) coupled with a PDA detector and ACQUITY UPLC ® BEH Shield RP18 column (2.1 × 100 mm, 1.7 µm).…”

Review on the Regulation of Plant Polyphenols on the Stability of Polyunsaturated-Fatty-Acid-Enriched Emulsions: Partitioning Kinetic and Interfacial Engineering

“…In addition, the types and concentrations of lipid concomitants that originally existed in oils also largely determine the antioxidative effects of polyphenols in emulsions. α-Tocopherol was reported to have synergistic or antagonistic effects with polyphenols, such as flavonoids and catechin, as a result of its renewability. ,, The amphipathic lipid concomitants in oils, such as phytosterols, phospholipids, plant pigment, etc., could also adsorb on the oil–water interface, which might alter the interfacial structure of the emulsion, thereby further complicating the effect and mechanism of action of polyphenols on the emulsion stability.…”

“…Generally, the water-soluble polyphenols with higher interfacial activity can be used in all types of emulsions as a result of their spontaneous interfacial adsorption. Moreover, the water-soluble polyphenols are more suitably used in O/W emulsions depending upon the interaction with emulsifiers or grafting with esters to promote their interfacial distribution in emulsions. ,,− Instead, the lipid-soluble polyphenols need to be used together with other water-soluble polyphenols in O/W emulsions to achieve a synergistic antioxidative effect. ,,,, Additionally, the oil- and water-insoluble polyphenols might be a potential material to stabilize Pickering emulsions. ,,,,− However, there is an uncertain influence on the emulsifying properties of emulsifiers and antioxidative activities of polyphenols in complex emulsion systems . The addition of tea polyphenols to milk significantly decreased the antioxidative activity of milk as analyzed by the FRAP method as a result of the sedimentation of tea polyphenol–whey protein complexes .…”